With the increasing popularity of mobile devices, it has become easier to reach a contact, regardless of their location. However, there are often situations in which a person attempts to reach a contact via their mobile device and the contact does not answer because their mobile device is in a silent mode or in a location (e.g., briefcase, purse) which makes the ringer inaudible or other notification signal undetectable. This can be frustrating since the contact may be available, however, he does not know someone is trying to reach him. This may even result in serious consequences if it is an emergency situation.
Corresponding reference characters indicate corresponding parts throughout the several views of the drawings.